Published patent application WO01/14012A1 discloses a flexible illuminator for external phototherapy. The flexible illuminator has at least one light generating source on a flexible substrate. The flexible illuminator further has a structure for diffusing light of the at least one light generating source and has a system for transferring heat away from a skin contact surface. In the discussed embodiments a plurality of light generating sources are provided. The back side of the flexible illuminator, which is, in use, a side of the flexible illuminator facing away from the skin of the treated person, provides a heat sink for absorbing the heat generated by the plurality of light generating sources. The heat sink works together with a heat barrier between the light sources and the skin to prevent that the skin contact surface is heated to a dangerous temperature by the heat of the light generating sources. Heat is transferred in a direction away from the person who is treated with the flexible illuminator.
The flexible illuminator of the cited art only comprises heat transferring means which transfers the heat of the light sources in a direction away from the treated person or animal. However, the contact area between the flexible illuminator and the skin of the treated person or animal may still become locally too hot or remain locally too cold. So-called hot and cold spots are inconvenient for the treated person or animal and may have a negative influence on the therapeutic effect of the flexible illuminator.